Br-PEG6-acid

Br-PEG6-acid is a polyethylene glycol-based PROTAC linker intermediate designed to connect targeting ligands to E3-recruiting moieties through a functional handle suitable for controlled conjugation. Its PEG-rich scaffold promotes aqueous compatibility and conformational flexibility, which can improve effective ternary complex formation in targeted protein degradation workflows. The subsequent points describe the key structural features and practical reactivity considerations for constructing PROTACs using this linker.

Structure: The linker comprises a brominated terminal group attached to a PEG chain terminating in a carboxylic acid. It contains repeating ether linkages that confer hydrophilicity and chain flexibility, along with a terminal alkyl bromide and a carboxylate-capable functional group for further derivatization.

Reactivity: The carboxylic acid can be activated for amide or ester bond formation using standard coupling strategies, while the brominated terminus can serve as an electrophilic site for nucleophilic substitution with appropriate nucleophiles under mild to moderate conditions. Typical PROTAC synthesis employs dry polar organic solvents, base-mediated activation for acyl coupling, and careful control of stoichiometry and temperature to minimize side reactions.